Process for producing highly crimped viscose rayon

ABSTRACT

HIGHLY CRIMPED VISCOSE RAYON WITH IMPROVED RESISTANCE TO WATER IS PRODUCED BY XANTHATING WITH 24 TO 32% BY WEIGHT ON CELLULOSE OF CARBON DISULFIDE, ADDING TO THUS OBTAINED VISCOSE A COMBINATION OF MODIFIERS, SPINNING RIPENED VISCOSE HAVING A Y-VALUE OF49 TO 37 AND A HOTTENROTH NUMBER WITHIN 20 TO 10 AND CORRESPONDS TO A POINT ON THE ASCENDING PORTION OF THE HOTTENROTH NUMBER-RIPENING TIME CURVE, SAID POINT BEING WITHIN A RANGE WHERE THE DIFFERENCE OF HOTTENROTH NUMBER AT SPINNING FROM THE HOTTENROTH NUMBER AT THE PEAK OF SAID CURVE IS 1 OR LESS.

United States Patent Ofioe 3,729,371 Patented Apr. 24, 1973 3,729,371 PROCESS FOR PRODUCING HIGHLY CRIMPED VISCOSE RAYON Tadao Sasakura and Katuo Sakuma, Koriyama, Japan, assignors to Nitto Boseki Co., Ltd., Fukushima-shi,

Japan Filed Mar. 9, 1971, Ser. No. 122,387 Claims priority, appliscjltionapan, Sept. 9, 1970,

rm. Cl. nolrs/lo, 3/28 US. Cl. 161-173 8 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a process for producing highly crimped viscose rayon with improved resistance to water.

One of the present inventors had already applied a patent (U.S. Ser. No. 827,281) relating to a process for producing crimped viscose rayon having a high wet modulus. The present invention relates to a process for producing viscose rayon having still higher crimp than the fiber obtainable by the process according to said prior application. In the prior application the number of crimp has been expressed in terms of number of crimp in water (number/1 mm.), whilst in the present invention it is expressed in terms of number of crimp after drying (number/25 mm.). Between the number of crimp in water and that after drying, there exists the following relationship: when compared on the same basis of denier and length of the fiber, a fiber having a number of crimp in water of about 20/100 mm. shows after drying about twice as much number of crimp (i.e. number of crimp after drying of about 40/100 mm.); and fibers having a number of crimp in water of 20 or less per 100 mm. show twice or more number of crimp after drying.

Formerly, viscose rayon had been unsatisfactory in resistance to water, and the dimensional stability of the fabric manufactured therefrom had also been unsatis factory. Since then various processes were proposed and as a result the resistance of viscose rayon to water was much improved, accompanied by, however, a decrease in the crimping property. The improvement of the resistance to water of viscose rayon in highly crimped state has not been fully developed yet.

Crimp is an important property of the fiber, because the quality of fabrics, blankets, carpets, non-woven fabrics, etc., is improved when a crimped yarn is used. However, the highly crimped viscose rayon now commercially available has no satisfactory resistance to water, and is inferior in the dimensional stability when woven into a fabric.

With respect to the resistance to water, the wet modulus at elongation (hereinafter referred to as 5% W.M.) is used as a measure for evaluating a fiber. To improve the resistance to water, it is necessary to increase the 5% W.M. of the fiber. As a result of studies on the development of a highly crimped fiber with improved resistance to water, the present inventors have succeeded in inventing a highly crimped fiber which has a 5% W.M.

comparable with or even superior to cotton (compared on the same denier basis).

The present invention relates to a process for producing viscose rayon, which is characterized by adding a specific combination of modifiers to a low -value viscose which is obtained by xanthating with reduced amount of carbon disulfide, ripening said viscose until a conditional Hottenroth number are attained, and then spinning the resulting viscose into a spinning bath of the sulfuric acid-sulfate type containing zinc.

When the cross-section of the fiber obtained according to the present invention is skin-dyed in the ordinary way, it is observed that, as is shown in FIG. 1, the skin on one side is thin while the skin on the opposite side is thick, and hence the cross section is so-called morphologically asymmetrical to a high degree. The fiber posesses excellent crimping tendency due to said cross-sectional shape. The 5% W.M. of the fiber is comparable with or superior to that of cotton (compared on the same denier basis) and, moreover, is not liable to be fibrillated. The fiber has also a high tenacity and an adequate elongation so that it shows an excellent performance when used for woven or knitted fabrics, blankets, carpets, non-woven fabrics, sanitary cotton substitutes, etc.

The invention is disclosed hereunder in more detail.

FIGS. 1 and 2 are both enlarged cross-sectional views of skin-dyed fibers. FIG. 1 is an enlarged cross-sectional view of the fiber obtained according to the present invention. FIG. 2 is a cross-sectional view of a highly crimped viscose rayon available on the market. FIG. 3 is a diagram showing Hottenroth number in relation to ripening time. FIG. 4 is a diagram showing wet modulus in relation to denier of the fiber. FIG. 5 is a diagram showing number of crimp in relation to denier of the fiber.

The present invention relates to a process for producing a highly crimped viscose rayon with improved resistance to Water, which comprises xanthating with 24 to 32% by weight on cellulose of carbon disulfide, adding to the viscose obtained a combination of modifiers selected from three groups, using each at least one modifier from all of the three groups, of which the first group consisting of zinc compounds, cadmium compounds, lead compounds and ferrous compounds (hereinafter referred to as first group modifiers), the second group consisting of polymers and copolymers of alkylene oxides (hereinafter referred to as second group modifiers), and the third group consisting of alkylene oxide derivatives of diamines and of polyamines (hereinafter referred to as third group modifiers); spinning the ripened viscose having a 'y-value of 49 to 37 and a Hottenroth number (hereinafter referred to as HZ.) which is within the range of 20 to 10 and which satisfies the following condition, into a spinning bath of the sulfuric acid-sulfate type containing a large amount of zinc, and stretching in the second bath.

The change in H2. as a function of ripening time of the viscose obtained according to the present invention is represented by the curve as shown in, for example, FIG. 3. The expression H.Z. which satisfies the following condition, referred to above, means such H.Z. that is rep resented by a point on the ascending portion of said curve, said point being within a range where the difference of H2. at the time of spinning from the I-LZ. at the peak of the curve is one or less (hereinafter referred to as conditional ripeness).

The amount of carbon disulfide to be added in xanthating is 24 to 32%, preferably 26 to 30% by weight on cellulose.

The amount of carbon disulfide affects the fiber quality of the viscose rayon. Regarding the crimp as an example, when said amount exceeds 30%, the number of crimp begins to decrease and when said amount exceeds 32% the highly crimped fiber of the present invention can no longer be obtainable.

As the first group modifier to be added to the viscose, any compound selected from zinc compounds, cadmium compounds, lead compounds, and ferrous compounds is effective so far as it is soluble in water or an alkali and is able to be added to the viscose in an amount of 1% or more by weight on cellulose in terms of weight of the metallic element. Examples of effective compounds include sodium zincate, zinc sulfate, lead oxide, cadmium acetate, ferrous sulfate, zinc oxide, zinc hydroxide, zinc acetate, cadmium sulfate, cadmium chloride, cadmium nitrate, ferrous chloride, lead nitrate, etc. The amount to be added is 1 to 10%, preferably 2 to 6% by weight on cellulose in terms of weight of the metallic element. If two or more compounds are to be added, the total amount shall be 1 to 10%, preferably 2 to 6% by weight. When the first group modifiers are added in an amount which falls outside said range, there is hardly expectable a sufficient combined effect with the second and third group modifiers for obtaining a highly crimped fiber with improved resistance to water. The modifier is added preferably after termination of the xanthating.

By adding to the viscose one or more types of compounds selected from the above-mentioned zinc compounds, cadmium compounds, lead compounds, and ferrous compounds, together with such an alkylene oxide polymer or copolymer, and an alkylene oxide derivative of a diamine or polyamine as described hereinafter, there were obtained viscose rayon fibers such as, for example, a 1.5 denier fiber having a 5% W.M. of 0.9-1.2 g/d. and a number of crimp after drying of 13l8/25 111111., and a 10 denier fiber having a 5% W.M. of 0.55- 0.65 g./d. and a number of crimp after drying of 5-8/25 min., as shown in Table 1 set forth hereinafter. In the case where a cadmium compound or a ferrous compound was used, there appeared a disadvantage of discoloration in the resultant viscose rayon fibers, although the discoloration was bleachable by scouring. n the other hand, in the case where a zinc compound was used, a satisfactoryfiber without any discoloration due to zinc compound was obtained.

The second group modifiers are polymers or copolymers of alkylene oxides including, for example, polyethyleneglycols (hereinafter referred to as PEG), Polypropyleneglycols (hereinafter referred to as PPG), c0- polymers of ethylene oxide and propylene oxide, and the like. The amount to be added is 0.5 to 10%, preferably 1 to 7% by weight on cellulose. If two or more compounds are to be added, the total amount shall be 0.5 to 10% by weight, preferably 1 to 7% by weight.

The third group modifiers are alkylene oxide derivatives of diamines and polyamines including, for example, an amine derivative obtained by reacting 1 mole of ethylenediamine with 4 moles of ethylene oxide (hereinafter referred to as EDA+4EO), an amine derivative obtained by reacting 1 mole of diethylenetriamine with 5 moles of propylene oxide (hereinafter referred to as DETA-l-SPO) an amine derivative obtained by reacting 1 mole of diethylenetriamine with 5 moles of ethylene oxide (hereinafter referred to as DETA+5EO), an amine derivative obtained by reacting 1 mole of pentaethylenehaxamine with 6 moles of ethylene oxide (hereinafter referred to as PEHA+ 6E0), an amine derivative obtained by reacting 1 mole of ethylenediamine with 4 moles of propylene oxide (hereinafter referred to as EDA+4EO+2PO), an

derivative obtained by reacting 1 mole of ethylenediamine with 4 moles of ethylene oxide and 2 moles of propylene oxide (hereinafter referred to as EDA-l- 4EO-I-2PO), an amine derivative obtained by reacting 1 mole of p-xylenediamine with 4 moles of ethylene oxide (hereinafter refer- 4 red to as p-XDA-I-4EO), an amine derivative obtained by reacting 1 mole of ethylenediamine with 1 mole of ethylene oxide' and 3 moles of propylene oxide (hereinafter referred to as EDA+1EO+3PO*), an amine derivative obtained by reacting 1 mole of propylenediamine with 4 moles of ethylene oxide (hereinafter referred to as PDA+4EO'), etc. The amount to be added is 1 to 10%, preferably 2 to 5% by weight on cellulose. If two or more compounds are to be added, the total amount shall be 1 to 10% by weight, preferably 2 to 5% by weight.

In the present invention, use should be made of a combination of each at least one compound selected from all of three groups, namely, the first group modifiers, the second group modifiers and the third group modifiers; otherwise the crimping tendency, 5% W.M., and tenacity of the fiber are deteriorated.

Viscosities of the viscose within the range of 50 to 500 seconds, as measured by the falling ball viscosimeter, are suitable for spinning, whereas viscosities higher than 500 seconds are unpreferable for spinning-technological and economic reasons.

At the time of spinning, the y-value should be 49 to 37 and the ripeness should be such that H.Z is 20 to 10 and corresponds to a point on the ascending portion of the H.Z.-ripening time curve, said point being within a range where the difference of H2. at the time of spinning from the HZ. at the peak of the curve is one or less. In the case where the difference of H.Z. at the time of spinning from the H1. at the peak of said curve is greater than one, a highly crimped viscose rayon is not obtained even if H1. is 20 to 10 and the ripeness corresponds to a point on the ascending portion of the curve. It is to be noted that the ripeness corresponding to said conditional H.Z. cannot be found by measuring the salt point. For example, as shown in Example 5, each H.Z. at points A and B (FIG. 3) are within the range of 20 to 10, but the H1. at point B does not meet the requirement of the conditional H.Z. Therefore, when the viscose at point B is spun, the crimp of the resulting fiber is markedly deteriorated.

The spinning speed is preferably lower than m./ min., to avoid the formation of an abnormal fiber.

While the concentrations of sulfuric acid and sodium sulfate in th first spinning bath varies according mainly to the composition of the viscose, the preferable concentrations in the case of a viscose with ordinary economical composition are 3 to 8% by weight for sulfuric acid and 5 to 20% by weight for sodium sulfate. The concentration of zinc sulfate in the first spinning bath is 1 to 10% by weight, preferably 2 to 5% by weight. When the concentration of Zinc sulfate is less than 1%, the fiber of the present invention cannot be obtained, whilst higher concentrations are uneconomical because of the increased amount of zinc sulfate carried off by the fiber emerging from the bath. The temperature of the bath is preferably 20 to 50 C. in view of heat economy, and the immersion length is preferably longer than 10 cm.

In the second bath, the concentration of sulfuric acid is 0.1 to 12% by weight, the concentration of zinc sulfate 0 to 10% by weight, the concentration of sodium sulfate 0 to 15% by weight, and the temperature 70 to C., these conditions being the same as in the conventional processes. In this bath the filaments are stretched and regenerated, and thereafter scoured and dried in ordinary ways.

According to the present process disclosed in detail in the foregoing, may be obtained viscose rayon fibers having the 5% W.M. and number of crimp within the ranges shown in Table 1. FIGS. 4 and 5 are the diagrammatical representation of the ranges shown in Table 1. FIG. 4 shows the relationship between the denier and the 5% W.M. FIG. 5 shows the relationship between the denier and the number of crimp after drying.

TABLE 1 1.5 denier 3 denier 6 denier 10 denier 5% W.M., g./d 0. -1. 2 0. 65-0. 9 0. 6-0. 7 0.55-0.65 Number of crimp after drying, N/25 mm..." 13-18 11-16 7-12 -8 Compared with the fiber of this invention, the 1.5 denier fiber shown in the pending application U.S. Ser. No. 827,281 has a higher 5% W.M. of 1.01.5 g./d. but has a far lower number of crimp in water of 12-25/ 100 mm. (corresponding to a number of crimp after drying of 6-12/ 25 mm.). Although in Table l were shown properties of fibers of 1.5 to deniers, it is, of course, possible to produce fibers finer than 1.5 denier or thicker than 10 denier. In the latter two cases, as is predictable from the results shown in Table 1, 5% W.M. and number of crimp increase as the denier is decreased, and

in an ordinary way to give the fiber A. In a similar manner, but using 5% of zinc oxide dissolved in sodium hydroxide and 2% of PEG having a molecular weight of 1,000 as the modifiers, a viscose was obtained, which was similarly spun, stretched, scoured, and dried to give the fiber B. Similarly, there were obtained the fiber C using 3% 0f (DETA-l-SPO) and 2% of PEG having a molecular weight of 1,000, and the fiber D using 5% (in terms of zinc) on cellulose of zinc oxide dissolved in sodium hydroxide and 3% of (DETA+5PO). The characteristics of these fibers were as shown in the following table, wherein the characteristics of a commercial highly crimped rayon was also included for comparison. FIGS. 1 and 2 show the enlarged cross-sectional views of the fiber A and a commercial highly crimped rayon respectively, the fibers having been skin-dyed in any ordinary way.

Dry Dry elon- Wet Wet elon- Knot Number of tenacity, gation, tenacity, gation, tenacity, 5% W.M., crimp per Denier g./d. percent g./.d. percent g./d. g./d. 25 mm 1h 1 l iiiiigiiiia iin i 3 2. 5 21 1. 5 25 1. 4 0. 13

EXAMPLE 2 conversely, 5% W.M. and number of crimp decrease as the denier is increased.

Thus, by use of fibers of the present invention, there may be produced various kinds of textile products including woven fabrics, knitted fabrics, blankets, carpets sanitary cotton substitutes, etc., which are excellent in resistance to water, dimensional stability, resilience, liveliness, and hand.

The invention is further illustrated below by reference to examples, which are mere examples of preferable embodiments of the invention and are, of course, not to be construed as limiting the scope of the invention. In examples, all percentages are by weight.

EXAMPLE 1 A wood pulp having a polymerization degree of about 800 was steeped in a 17.5% solution of sodium hydroxide at 20 C. for 60 minutes, then pressed to the weight 2.7 times as much as the weight of air-dried pulp, and shredded at 20 C. to 53 C. for 60 minutes. To the alkali cellulose thus obtained, was added 29% on alkali cellulose of carbon disulfide and xanthating was effected at 20 to 26 C. for 150 minutes. To the resulting mass, were added 5% (in terms of zinc) on cellulose of zinc oxide dissolved in sodium hydroxide, 3% of (DETA+SPO) 2% of PEG having a molecular weight of 1,000, a sodium hydroxide solution, and water, and dissolution was eifected at 15 C. for 3 hours to obtain a viscose containing 6.9% of cellulose and 6.1% of alkali and having a viscosity of 240 seconds as measured by the falling ball method at 20 C. The viscose was filtered, deaerated, and then ripened at 15 C. to a ripeness when a -value of 47 and a conditional H.Z. of 16 were reached. Then The same viscose as that used in Example 1 for producing the fiber A was spun from a nozzle having 1,200 holes, each 0.10 mm. in diameter, at a spinning speed of 25 m./min. into a first spinning bath at 35 C., which contained 5.1% of sulfuric acid, 8.5% of sodium sulfate, and 2.7% of zinc sulfate, and the filaments were stretched 115% in the second bath containing 5% of sulfuric acid, 0.5% of sodium sulfate, and 1% of zinc sulfate at C. Thereafter the filaments were scoured and dried in an ordinary way to give a fiber, the characteristics of which were as shown in the following table.

Denier 6 Dry tenacity, g./d. 4.0 Dry elongation, percent 15 Wet tenacity, g./d. 2.7 Wet elongation, percent 17 Knot tenacity, g./d. 1.6 5% W.M., g./d. 0.7 Number of crimp per 25 mm 9 EXAMPLE 3 The same viscose as that used in Example 1 for producing the fiber A was spun from a nozzle having 1,200 holes, each 0.13 mm. in diameter, at a spinning speed of 20 m./ min. into the first spinning bath at 35 C. with an immersion length of 80 cm., which contained 5.3% of sulfuric acid, 9.5% of sodium sulfate, and 2.6% of zinc sulfate, and the filaments were stretched in the same second bath as that used in Example 2. Thereafter the filaments were scoured and dried to give a fiber, the characteristics of which were as shown in the following table. In the table were included also the characteristics of a commercial highly crimped rayon for comparison.

Dry Dry elon- Wet Wet elon- Knot Numberof tenacity, gation, tenacity, gation, tenacity, 5% W.M., crimp per Denier g./d. percent g./d percent gJd. g./d. 25 min This example 10 3. 6 15 2. 3 l7 1. 4 0. 61 7 Commercial highly crimped ray0n 15 2.0 20 1.1 28 1.0 0.25 7

the viscose was spun from a nozzle having 1,500 holes, EXAMPLE 4 each 0.07 mm. in diameter, at a spinning speed of 30 7O m./sec. into a first spinning bath at 35 C., which contained 5% of sulfuric acid, 13% of sodium sulfate, and 2.6% of zinc sulfate, and the filaments were stretched in the second bath containing 3% of sulfuric acid The same viscose as that used in Example 1 for producing the fiber A was spun from a nozzle having 1,500 holes, each 0.05 mm. in diameter, at a spinning speed of 32 m./min. into the first spinning bath at 36 C., which at 96 C. Thereafter the filaments were scoured and dried 75 contained 4.4% of sulfuric acid, 11% of sodium sulfate,

and 2.9% of Zinc sulfate, and the filaments were stretched 140% in the second bath containing 1% of sulfuric acid at 97 C. Thereafter the filaments were scoured and dried in an ordinary way. The characteristics of the fiber obtained were as shown in the following table.

Denier 1.5 Dry tenacity, g./d. 4.7 Dry elongation, percent 12 Wet tenacity, g./d. 3.4 Wet elongation, percent 14 Knot tenacity, g./d. 2.4 W.M., g./d. 1.0 Number of crimp per 25 mm W 14 EXAMPLE 5 To the alkali cellulose obtained in the same manner as in Example 1, was added 27% of carbon disulfide, and

xanthating was effected at to C. for 160 minutes. i

To the resulting mass, were added 4.8% of sodium zincate, 2.9% of (EDA-l-4PO), 2% of PPG having a molecular weight of 400, an aqueous solution of sodium hydroxide, and water, and dissolution was effected at 20 C. for 3 hours to obtain a viscose containing 7% of cellulose and 6% of alkali. The viscose was filtered, deaerated and then ripened. The HZ. was measured as a function of the ripening time to obtain a diagram as shown in FIG. 3. In FIG. 3, of the two kinds of viscose at points A and B, the viscose at point A had a H.Z. which was within the range of 20 to 10 and also met the requirement of the conditional 111., whereas the viscose at point B had a H.Z. which was also within the range of 20 to 10 but did not meet the requirement of the conditional H1. The 'y-values of the viscose at A and B were 43 and 46 respectively. Each of the viscose at points A and B was spun into the first spinning bath at 36 C.; which contained 4.3% of sulfuric acid, 11% of sodium sulfate, and 3% of zinc sulfate, and the filaments were stretched 120% in the same second bath as in Example 4. Thereafter the filaments were scoured and dried in an ordinary way. Fibers A and B were obtained from the viscose at points A and B respectively. The characteristics of each fiber were as shown in the following table.

fiber, the characteristics of which were as shown in the following table.

The alkali cellulose obtained in the same manner as in Example 1 was xanthated with 29% of carbon disulfide at 20 to C. for 120 minutes. Then thereto were added 4.8% of ferrous chloride, 3% of (EDA+4PO), 2% of PEG, an aqueous sodium hydroxide solution, and water. The dissolution was effected at 18 C. for 3 hours to obtain a viscose containing 7% of cellulose and 6% of alkali. The viscose was filtered, deaerated, and then ripened until a -value of 46 and a condtional HZ. of 15 were reached. Said viscose was spun from a nozzle having 1,500 holes, each 0.06 mm. in diameter, into the first spinning bath containing 4.3% of sulfuric acid, 14.5% of sodium sulfate, and 2.5% of zinc sulfate, at C. and at a spinning speed of 30 m./min. The filaments were stretched 130% in the second bath at 96 C., which contained 3% of sulfuric acid, 1% of sodium sulfate, and 2% of zinc sulfate. Thereafter the filaments were scoured and dried in an ordinary way to obtain a fiber, the characteristics of which were as shown in the following table.

Denier 2.5 Dry tenacity, g./d. 4.0 Dry elongation, percent 12 Wet tenacity, g./d. 3.0 Wet elongation, percent 13 Knot tenacity, g./d. 1.9

5% W.M., g./d. 0.80 Number of crimp per 25 mm. 13

What is claimed is: 1. A process for producing highly crimped viscose rayon with improved resistance to water, which comprises Dry Dry elon- W et. Wet elon- Knot Number of tenacity, gation, tenacity, gation, tenacity, 5% W.M., crimp per Denier g./ percent g./d. percent gJd. g./d. 25 mm.

EXAMPLE 6 (a) xanthating alkali cellulose with 24 to 32% by weight The alkali cellulose obtained in the same manner as in Example 1 was xanthated with 30% of carbon disulfide at 20 to 30 C. for 120 minutes. Then thereto were added 4.9% (in terms of lead) on cellulose of lead'oxide dissolved in a sodium hydroxide solution, 3.1% of (EDA-l-4EO), 2% of PEG, an aqueous solution of sodium hydroxide, and water. The dissolution was effected at 16 C. for 3 hours, to obtain a viscose containing 7% of cellulose and 6% of alkali. The viscose was filtered, deaerated, and then ripened until a 'y-value of and a conditional H.Z. of 12 were reached. Said viscose was spun from a nozzle having 1,500 holes, each 0.06 mm. in diameter, into the first spinning bath containing 4.8% of sulfuric acid, 9.5% of sodium sulfate, and 3.1% of zinc sulfate, at 36 C. and at a spinning speed of 30 m./ min. The filaments were stretched 125% in the second bath containing 3% of sulfuric acid at 96 C., and thereafter scoured and dried in an ordinary way, to obtain a on cellulose of carbon disulfide, (b) adding to the re sulting viscose 1 to 10% by weight (in terms of weight of metal on cellulose) of at least one compound selected from the group consisting of sodium zincate, zinc sulfate, lead oxide, cadmium acetate, ferrous sulfate, zinc oxide, zinc hydroxide, zinc acetate, cadmium sulfate, cadmium chloride, cadmium nitrate, ferrous chloride, and lead nitrate; 0.5 to 10% by weight on cellulose of at least one number selected from the group consisting of polymers of alkylene oxide and copolymers of two or more alkylene oxides; and 1 to 10% by weight on cellulose of at least one compound selected from the group consisting of alkylene oxide derivatives of diamines and polyamines, (c) ripening the resulting viscose until there are attained a -value of 37 to 49 and a Hottenroth number of 10 to 20, provided which Hottenroth number correspond to a point on the ascending portion of the Hottenroth number-ripening time curve, said point being within a range where the differences of Hottenroth number at the time of spinning from the Hottenroth number at the peak of said curve is one or less, (d) spinning the ripened viscose into the first bath containing 3 to 8% by weight of sulfuric acid, 5 to 20% by weight of sodium sulfate, and 1 to 10% by weight of zinc sulfate, and (e) stretching the spun filaments in the second bath at 70 to 100 C., which contains 0.1 to 12% by weight of sulfuric acid, to 15% by weight of sodium sulfate, and 0 to 10% by weight of zinc sulfate.

2. A fiber produced by the process according to claim 1, which has a wet modulus at elongation and number of crimp as shown by the hatched part in FIGS. 4 and 5, or a fibrous product containing said fiber.

3. A process according to claim 1, wherein 2 to 6% by weight of at least one compound selected from the group consisting of zinc compounds, cadmium compounds, and lead compounds are added.

4. A process according to claim 1, wherein the polymer or copolymer of alkylene oxide is selected from the group consisting of polyethylene glycols, polypropylene glycols, and copolymers of ethylene oxide and propylene oxide.

5. A process according to claim 1, wherein 1 to 7% by weight of at least one member selected from the group consisting of polymers and copolymers of alkylene oxides are added.

6. A process according to claim 1, wherein the alkylene oxide derivatives of diamines and polyamines are selected from amine derivatives obtained by reacting 1 mole of ethylenediamine with 4 moles of ethylene oxide, amine derivatives obtained by reacting 1 mole of diethylenetriamine with 5 moles of propylene oxide, amine derivatives obtained by reacting 1 mole of diethylenetriamine with 5 moles of ethylene oxide, amine derivatives obtained by reacting 1 mole of pentaethylenehexamine with 6 moles of ethylene oxide, amine derivatives obtained by reacting 1 mole of ethylenediamine with 4 moles of propylene oxide, amine derivatives obtained by reacting 1 mole of ethylenediamine with 4 moles of ethylene oxide and 2 moles of propylene oxide, amine derivatives obtained by reacting 1 mole of p-xylylenediamine with 4 moles of ethylene oxide, amine derivatives obtained by reacting 1 mole of ethylenediamine with 1 mole of ethylene oxide and 3 moles of propylene oxide, and amine derivatives obtained by reacting 1 mole of propylenediamine with 4 moles of ethylene oxide.

7. A process according to claim 1, wherein 2 to 5% by weight of an alkylene oxide derivative of a diamine or polyamine are added.

8. A process according to claim 1, wherein the viscosity of the viscose is to 500 seconds as measured by the falling ball methods at 20 C.

References Cited UNITED STATES PATENTS 2,780,512 2/1957 Inoshita. 264-188 2,835,551 5/1958 Kosuge 264-188 3,083,075 3/1963 Saxton et a1. 264-188 3,277,226 10/1966 Bockno et al 264-188 3,494,996 2/1970 Stevens et a1 264-188 JAY H. WOO, Primary Examiner US. Cl. X.R. 

